Hi Karl !
As sb., who saw the flight live (-> I was there
and flew 2 birds, as you can see in this thread), I´ll try to answer your question.
Rolli (he built the Ariane V) used Held1000 ((or H5k.. hhm)) motors in the boosters.. Somewhere in this Forum I wrote pretty much about them.. hhmm..
The Held1000 (H1k) is a German BP Motor with only 15mm Diameter, which burns slightly over 5 seconds.
This makes him to a C2- Motor.
These motors don´t have a delay or ejection Charge, but in the H5k (burn´s ~ 3sec., 25mm motor) you can epoxy an A,B or C in the "normal Delay" Site of the motor (18mm motors fit inside the paper tube of the H5k), which brings the ejection ! Very easy and it works very good.
I don´t know, why the flame looks so strange in this case (normaly its a normal A,B,C size Flame ), but I think, that:
a) the motor was shortly before the end of burn (Rolli lets the Booster stand 3sec. on the Rail, bevore he ignites the Vulcain/ middle motor)
b) the Transitions on the end of the Booster makes some strange wind profiles ..
There should be no problem, to fly these motors in the U.S., perhaps a customer wants to take these in the programm in the U.S. ?!
Marxi